Application Command Browser in Dev Portal

[jnsougata]

There's certainly no way for now to see what commands the bot has and manage a particular command externally without writing a program. I wonder if we can manage commands for a bot from the dev portal. Let's say we want to delete a command. We can just head over to the dev portal and delete it. It will be more convenient than writing a script to delete it. We should also be able to edit the basics of a command like description default_member_perms dm_access etc.